Mistake in the comment.
Add detect method to orcus_gnumeric, and use scope object for gzfile.

The detection code will come later. Decompressing a gzip in memory
needs a bit more work.
Add skeleton code for xls xml detection.

It still doesn't detect anything yet.
Prevent infinite loop in case the magic number is not found.
Detect Excel XML format for real.
Notes on how to implement in-memory gzip handling.
Note on using boost iostreams to do in-memory gzip decompression.
Use boost.m4 to simplify boost library detection during configure.
Use boost::iostreams to decompress gzipped stream in memory.
Use common function to decompress gzipped stream for gnumeric files.
Remove unused header includes.
We don't need this.
Set up detection handler skeleton for orcus-gnumeric.
Detect gnumeric file type.
Add test for gnumeric file format detection.
Class description.
Use boost::program_options to handle inputs for orcus-ods.

Options are not being handled yet.
Check the input values, and honer output directory path.
We don't need this file.
boost::program_options required only --with-tools.